The present invention relates generally to devices suitable for use in testing printed circuit boards. Specifically, the present invention relates to an overclamp assembly for positioning a probe over a component on a printed circuit board for testing the component.
Electronic components, such as silicon chip integrated circuits, other semiconductor devices, or connectors are subject to early failure during their life cycle. Thus, producers of printed circuit boards containing electronic components have found it cost-effective to test the printed circuit boards and electronic components prior to shipment to an end-user or the like. By such testing, and by the elimination of failed or under performing electronic components, the reliability of printed circuit boards is greatly enhanced.
Often times, a spring probe is used in testing the electronic components. An operator positions the probe on top of the component. The probe is electrically connected to a test device such as a test computer which applies signals to the component, or receives signals from the component, through the probe. Based on the signals applied and received, the test system measures characteristics of the component.
Sometimes, the operator must hold the probe against the component for a period of time. Also, the operator may be required to test several circuit boards over a given time.
It has been found advantageous to use a clamp to position and hold the probe in place during testing. Several clamps are known. One clamp which functions similar to a drill press, moves the probe through a longitudinal travel path when placing the probe against the component and removing the probe from the component. However, due to the limited range of motion in the longitudinal direction which is conventional with such a clamp, such a clamp-may not provide the necessary longitudinal clearance for exchanging printed circuit boards.
Pivotably mounted probes, on the other hand, move along an arc relative to the component in order to engage, and disengage from, the component. Thus, pivotable clamps swing out of the way and provide necessary clearance to exchange circuit boards. However, the arcuate motion of the probe when descending upon (and engaging) a component is undesirable because other components which are proximate the component set for testing are often in the path of the swinging probe. Further, just as the probe contacts the component, the probe travels through the remaining arc required for full engagement with the component. This causes the probe to "scrape" along the surface of the component under test.
Known clamps that provide the probe with an arcuate motion for clearance and a longitudinal path for positioning and accessibility require multiple and cumbersome steps for proper operation. For example, such clamps typically require the actuation of two or more levers in order to move the clamp into and out of engagement with the component. Such additional steps reduce the efficiency of an operator when testing printed circuits over a given period of time.